Air conditioning system



Sept. 30, 1941. H. R. sEwELL AIR CONDITIONING SYSTEM 2 sheets-sheet 1 L Filed Aug. 15, 1959 INVENTOR.v HEM/QV /QGEM/Lb ATTORNEY,

QWRE 9,50%

Filed Aug. 15A, 1959 2 Sheets-Sheet 2 Patented Sept. 30, 1941 Am coNn'rrloNmG SYSTEM Henry R. Sewell, Norwell, Mass., assignor to B. F.

Sturtevant Mass.

Company, Hyde Park, Boston,

Application August 15, 1939, Serial No. 290,167

. 13 Claims. This invention relates to the conditioning of air for comfort and relates more particularly to the combination of a central dehumidifier and local sensible coolers with lcontrols for maintaining def sired 'conditions of temperature and humidity at minimum expense.

In the past it has generally been the practice to dehumidify outdoor air and air recirculated from the space served, to a predetermined low dew point and after reheating the dehumidied air by mixture with by-pass air or by steam, to supply the mixed air into the space served. This has required not only large fans and large devhumidiller's for handling large volumes of air,

but the supply ducts were large, and recirculated air and by-pass air ducts were required.

According to this invention dehumidied outdoor air is supplied to the space served, and sensible coolers in the space served take care of sensible heat gains in the space through recirculation of and the cooling of the air in the space.

A feature of the invention resides in varying the volume ,of dehumidified air supplied to the space served proportional to the moisture gains in the space thus meeting Ventilating requirements by varying the volume of outdoor air conformably with the numberof occupants of the space served.

Another feature of the invention resides in so adjusting the relation between the dew point temperature of the conditioned air and the temperature of the local sensible coolers that no vcondensation at the sensible coolers can take place.

In a preferred embodiment of the invention employing hygroscopic dehumidiilcation this is accomplished by controlling thedew point of the air supplied into the space served, by controlling the vapor pressure of the absorbent'solution, and by independently controlling the temperature oi the cooling fluid supplied to the sensible coolers.

Anothenfeature of the invention resides in varying the dew point temperature of .the dehumidied air conformably with changes in the temperature of the outdoor air, so that the dew point temperature is raised when the outdoory temperature rises, and is lowered when the outdoor temperature falls. l

Another feature of the invention resides in providing refrigerative water cooling in an after cooler and in the local sensible coolers when the wet bulb temperature of the outdoor air is too high for evaporative cooling to be effective, and in supplying this cooling -eiiect through evap- Vorative cooling when the wet bulb temperature of the outdoor air is sudlciently low.

An object of the invention is supplying conditioned outdoor airv in volumes varying conformably with moisture gains and accordingly Vwith Ventilating requirements. Y Another object is to remove sensible heat gains in a space supplied with dehumidied outdoor air, without providing condensation in the space. Another object is controlling the operation of a central dehumidifier and local sensiblelcoolers in accordance with changes in outdoor air conditions.

Another object of the invention is to control they dew point temperature of the air delivered by a hygroscopic dehumidifier by adjusting the vapor pressure of the hygroscopic solution em? ployedf /Another object of the invention is to supply evaporatively cooled water to the after cooler of a hygroscopic air dehumidier and to associated local sensible coolers.

Other objects of the invention will be apparent from the following description taken with the drawings.

The invention will now be described with reference to the drawings, of which: l

Fig. 1 is a diagrammatic view of one embodiment of the invention employing hygroscopic dehumidication, and

Fig. 2 is a diagrammatic view of another embodiment of the invention employing refrigerative dehumidication. "With reference to Fig. 1, a hygroscopic solutionsuch, for example, as lithium chloride from the sumpf is circulated by the pump B through the pipe 1 into `the solution cooler-8 used in the cooling season, and then into the solution heater l used in the heating season and through the spray nozzles (not shown) in the air' conditionerV III. 'I'he solution returns through the pipe Il to the sump 5.

A portion of the solutiondrawn from the sump 5 by the pump 6 is by-passed through the pipe I2, through the heater I3 and concentrator I4 where excess moisture is evaporated, the concentrated solution returning through the pipe I5 to the sump 5. The fan I6 forces air .through the duct Il and concentrator Il to aid in the evaporation.

The cooling tower water after cooler I8 is a sensible cooler-receiving water through the pipe I9,valve 2l and pump 2| from the cooling tower 22. After passing through the -cooler I8 the water returns through the pipe 23 tothe cooling tower 22. A portion of the water from the cooling tower 22 is by-passed through the pipe 24 and valve 25 and solution cooler 8 following which it returns through the pipe 23v to the tower 22.

The evaporatively cooled water from the tower 22 removes sensible heat in the cooler |8 from the dehumidiedair, and cools in the cooler 8 way valve and is connected toI the pipe 33 which dehumidication by refrigeration, '1t was the l practice. to maintain a constant minimum dew point in the dehumidified air, and to vary the dry bulb temperature of the delivered air as required for comfort. 'This resulted inhaving to reheat air previouslycooled by refrigeration, and

in relatively great humidity iluctuations in the space served.

The'present invention by raising the dew point of the dehumidied air above a selected miniforms a by-pass around the evaporator cooler Y 26 for the purpose which will presently be explained.

A portion of the refrigerated water from the evaporator cooler 26 passes from the pipe 30 through the pipe 34 and valve 35 and into the local cooler 36 in the room or zone 31. The

water from the local cooler then passes through the pipes 38 and 33 back to the pump 21. i

'Ihe local cooler 36 is an element of the local sensible cooler 39 which also has the fan 4|),

recirculated air inlets 4| and dehumidifled air inlet 42. The sensible cooler 39 is one of several supplied with dehumidiiled outdoor air from the air conditioner I0, and recirculates the air within its room or zone 31 and mixes dehumidiiled outdoor air with the recirculated air in volume proportional to the occupants of the space 31 as will presently be explained.

The central fan 43 draws outdoor air through the ducts 44 and I9, air conditioner I0, and coolers I8 and 25 and supplies it through the main supply duct 45 and through'branch ducts such as 46 into each of the rooms or zones 31, served.

The typical space 31 contains the humidostat 4 connected by the line 41 to fa compressed air supply and controlling through the airline 48 and bell 49 the position of the damper 150 in the branch duct 46. As the moisture in the space varies above or below the desired standard, the humidostat 4 adjusts the damper 58 to admit more or less respectively, dehumidied air, through the duct 46 and inlet 42 into the local unit 39. The moisture gains vary with the occupants of the space 31 so'that the damper 58:

acts to vary the volume of outdoor air supplied in accordance with proper ventilating requirements.

The dry bulb master thermostat 5| in the outdoor air duct 44 is connected by the air line 52 to the compressed air supply and is connected by the air lines 53 and 54l to the wet bulb thermostat or hygrostat sub-stat 55 in the main supply duct 45. The sub-stat 55 is` connected by the air line 56 to the bells 51 and 58 which control the vapor pressure of the absorption liquid circulated through the air conditioner by adjusting the valves 25 and 59 to vary its temperature.

The valve 59 is in the steam pipe 60 connecting the solution heater 9 with the steam source 6| which is in service during the heating season.

The wet bulb thermostat 55, Vit could alternatively be a, humidostat, responds 'to changes in the humidity of the air in the main supply duct to maintain the desired standard by adjusting the vapor pressure of the absorption liquid mum, conformably with rises in outdoor air temperatures, accomplishes several results. The cooling load is reduced and fluctuations in rela- 'tive humidity are reduced. In addition as will be described in the followingiparagraph, the dry bulb temperature f of the air delivered to the enclosure served, and the temperature of the sensible cooler in the enclosure are raised conformably with rises inthe outdoor temperature. Thus comfort with minimum cost is obtained without danger of shocks due to excessive differences in indoor and outdoor temperatures.

The master thermostat is also connected by the air lines 53 and 62 with the dry bulb sub-stat 63 in the main air supply duct 45, and by the air line 53 with the dry bulb sub-stat 10 in the space 31, and .resets these thermostats comformably with outdoor dry bulb temperature changes.

The thermostat 63 is connected bythe air lines 66 to the bell 61 which adjusts the valve 20 in the water line I9 to the cooler I8', and by air line 68 to the bell 69 which adjusts the valve 32 in the `water line 30 to the cooler 25. The thermostat 63 thus controls the dry bulb temperature of the air in the supply duct 45.

The thermostat 10 in vthe space 31 is connected by the air line 1| to the bell `12 which adjusts the valve 35 in the refrigerated water pipe to the local cooler 36, and controls the temperature of the air delivered `by the local cooler, and adjusts the temperature of the air delivered by the local cooler conformably with outdoor temperature changes.

The dew point thermostat 65 in the mai supply duct 45 is connected to the compressed air supply by the air line 64 and is connected by the air line 13 to the sub-stat 14 in the refrigerated water pipe 30. The sub-stat 14 is connected by the air line 15 to the bell 16 which adjusts the three-way valve 3|. The sub-stat 14 controls the temperature of the refrigerated water through the pipe 36 to the central cooler 25 and local cooler 36 by adjusting Ythe valve 3| to mix chilled water from the evaporator cooler 26 with recirculated water by-passed through the pipe 33 around the cooler 26. The sub-stat 14 is adjusted bythe dew point thermostat 65 to control the temperature of the water supplied to the coolers 25 and 36 to prevent it having a temperature closely approaching the dew point temperature of the conditioned air. In this way no condensation cantake place at the coolers 25 and 36.

The evaporator cooler 26 receives a volatile refrigerant; through the pipe 11 and expansion valve 18, from the condenser 19 and compressor 88. The cooling tower 8| normally during refrigerating operation supplies water through the pump 82, pipe 83, valve 84 and pipe 85 to the lair is low enough for evaporative cooling to be effective, the wet bulb thermostat 89 which receives compressed air through the line 90, actuates the valve 81 through the bell 92 and air line 8| to close off the pipe 86 and to connect the pipe |02 with the pipe 88. It also actuates the valve 84 through the air line 93 and bell 94 to close off the pipe 85 and to connect the pipe 83 with the pipe |03. Atthe same time through the air lines 93, 95 and 96 it actuates the bell 91 to open the electric switch 98 to deenergize the compressor motor 99. At the same time through the air lines 93 and 95, it actuates the bell to open the electric switch |0|,to deenergize the pump motor 28.

The wet bulb thermostat 89 thus deenergizes the compressor 80 and the pump 21; discon-l tinues the ilow of water from the tower 8| through the condenser 19, and circulates the cooling tower water through the pipes |03 and |02 connecting with the pipes 30 and 33 respectively, through the central sensible cooler 25 and the local cooler 36 when the Wet bulb temperature of the outdoor air falls to a predetermined point. When the wet bulb temperature of the outdoor air rises above the predetermined point, the thermostat 89 actuates the above described controls to energize the compressor 80and plump` 21 and to route the cooling tower water through the condenser 19 instead of into cooling water circuit.

The embodiment iiiustrated by Fig. 2 utiuzcs refrigeration for dehumidication and utilizes recirculated air as by-pass air for reheating the dehumidied air prior to discharge into the supply ducts. The central conditioner |04 is supplied with refrigerated water from the evaporator cooler |05 by the action of the pump |06, through the pipe |01 and valve |08. The valve |08 is a three-way valve and is controlled through the air line |09 and bell ||0 by the duct thermostat acting as a dew point control, to mix refrigerated water from the pipe |01 with water recirculated through the air conditioner |04 by the pump |60 for maintaining the desired dew point temperature.

The dry bulb thermostat 2 in the outdoor air inlet of the conditioner |04 receives compressed air through an air line ||3 and is connected by the air lines ||4'` and ||5 with the thermostat which it adjusts conformably with changes in the temperature of the outdoor air.

'I'he outdoor thermostat ||2 is also connected by the air lines ||4 and 6 with the drybulb sub-stat I1 in the air lsupply duct ||8, and by the air lines I|4 and |8 with the dry bulb subthe sensible stat.. |20 in the room or zone |2|. It readjusts these sub-stats conformably with outdoor temperature changes.

The sub-stat ||1 is connected by the air line |22 to the bell |23 which adjusts the damper |24 in the by-pass air duct |25. It is also connected by the air line |22 to the bell |26 which adjusts the valve -|21 in the steam pipe |28 connecting the steam source |29 with the air heater |30 arranged between the conditioner |04 and the fan 3|. The valve |21 is adapted to start opening when the damper |24 has been adjusted to full open position with the sub-stat ||1 still calling for heat.

trolling the volume of refrigerated water to the cooler |35.

The pipe' |36 forms a water by-pass around the evaporator cooler |05 and connects with the three-way valve |31 in the refrigerated water line |34. 'I'he thermostat |38 in the'l refrigerated water line |34 adjusts through the bell |39, the valve 31 to control the mixture of' refrigerated water from the cooler around the cooler for maintaining a predetermined temperature of the water in the pipe |34.

'Ihe thermostat |38 is adjusted through the air line |40 by the thermostat to maintain the temperature of the water supplied through the pipe |34 to the local cooler`l35, above the dew point of the conditioned air supplied through the ducts ||8 and |4| so no condensation of moisture can take place upon the surface of the cooler |35. adjusted by the outdoor air thermostats adjustment of the thermostat I, it confonnably adjusts the thermostat |38.

'Ihe humidostat |42 is connected by the air line |43 to compressed air and by the air line |44 to the bell |45 Which adjusts the damper |46 in the duct |4I. 'I'he humidostat adjusts the damper |46 to vary the volume of dehumidified air supplied to the space 2| conformably with the moisture gain therein which varies with the number of occupants.

The cooling tower |41 supplies cold water through the pump -|48 and pipes |49 and |50, to the condenser |5| for cooling same. When the wet bulb temperature of the outdoor air is sufficiently low, the wet bulb thermostat |52 which is supplied with compressed air through the air line |53, adjusts through the air line |54 and bells |55 and |51, the three-way valves |56 and |58 respectively, to adjust the valves |56 and |58 to close oil` the flow of refrigerated water from the cooler |05 to the local cooler |35 and to connect the local cooler |35 to the cooling tower |41.

What is claimed is: v

1. An air conditioning system for a room comprising in combination, a central dehumidier, mean-s for passing outdoor air through said dehumidifier and into said room, a sensible cooler in said room, means including a dew point control responsive to the dew point temperature of the air from said dehumidier for adjusting in said dehumidier the dew point of the air passing therethrough, supply means for supplying a cooling fluid to said cooler, and means responsive to changes in the temperature of the outdoor air entering said dehumidifier for adjusting said dew point control and said supply means for increasing the dew dehumidiiied air and for increasing the temperature of said :duid conformably with increases in the temperature of the outdoor air.

2. An air conditioning system for a roem comprising in combination, means including a central dehumidifier for outdoor air into said room, a sensible cooler in said room, means Supplying a cooling uid to said cooler, means forincreasing the dew point temperature of the air delivered by said dehumidier conformably with increases .in the |05 with water by-passed- As the dew point control is point temperature of the supplying dehumidied V outdoor temperature, and means responsive to humidity, changes of the air in said room for -ing the temperature of the air leaving said dehumidifying means, means responsive to the dew point temperature of the air in said duct for adjusting said cooling means, volume control means for varying the volume of air delivered by said duct into said room, and means responsive to humidity changes in said room for adjusting said volume control means.

4. An air conditioning system for a room comprising in combination, a central vdehumidifier for dehumidifying outdoor air, means including a duct for 4supplying air from said dehumidier into said room, a local cooler in said room, cooling means for varying the temperature of said cooler,- hygroscopic dehumidifying means for varying the dew point temperature of the air in said dehumidifier, cooling means for decreasing the temperature of the air leaving said dev humidifying means, means responsive to the dew point temperature of the air in said duct for adjusting said cooling means and means responsive to temperature increases in the outdoor air for adjusting said dew point temperature responsive means for increasing the temperature at which it responds.

5. An air conditioning system for a room comprising in combination, means including a central dehumidifier for supplying dehumidied out- 'door air into said room, volume control means for varying the volume of outdoor air supplied by said dehumidifier.into said room, a cooler in said room, means for varying the effectiveness of said cooler, means including a thermostat in said room for controlling said last mentioned'means.

means for adjusting said volume control means conformably with humidity changes in said room, and means responsive to outdoor air temperature changes for adjusting said thermostat for increasing the temperatures at which it responds conformably with increases in outdoor temperatures.

6. An air conditioning system for a room comprising in' combination, a central dehumidifier for dehumidifying outdoor air, means including a duct connecting said dehumidifier and said room, means in said duct 'forvarying the temperatures of the air delivered by said dehumidifier, .a duct thermostat for controlling said last mentioned means, a cooler in said room, means .for varying the effectiveness of said cooler, a

room thermostat for controlling said last mentioned means, and an outdoor thermostat for adjusting said duct and room thermostats.

7. An air conditioning system for a 'room com- `prising in combination, a central dehumidifier for dehumidifying outdoor air, means for vary- `ing the dew point temperature of the air :in said dehumidifier, means including a dew point thermostat responsive to the dew point temperature of the air delivered by said dehumidifier for controlling said means, means including a duct connecting said dehumidifier and said room, means in said duct for varying the dry bulb temperature of the air delivered by said dehumidifier, means including a duct thermostat for adjusting said last mentioned means, a local cooler in said room, means for varying the effectiveness of said cooler, means including a room thermostat for controlling said last mentioned means, and means including an outdoor thermostat connected to said dew point thermostat, said duct thermostat and said room thermostat for 4adjusting same ,for changes in outdoor temperature for increasing the temperatures vat which they operate conformably with increases in the outdoor temperature.

8. An air conditioning system for a room comprising in combination, a central dehumidifier for dehumidifying outdoor air, means including a duct connecting said dehumidifier and room. means for varying the dew point temperature of the air in said dehumidifier, means including a.`

duct thermostat for controlling said last mentioned means, means in `said duct for varyingthe( a temperature of the air delivered by said dehumidifier, means including a second'duct thermostat for controlling said last mentioned means, and means including an outdoor airthermostat for adjusting said duct thermostats for increasing the temperatures at which they operate, conformably with increases in the outdoor.

tioned means, means in said duct for varying the temperature of the air delivered by said dehumidifier, means including a second duct thermostat for controlling said last mentioned means,

.a local cooler in said room, means for varying the effectiveness of said cooler, means including a room thermostat for 'controlling said last mentioned means, and means including an outdoor thermostat for adjusting said thermostats for increasing the temperatures atwhich they operate conformably with increases in the outdoor temperature.

,10. An air conditioning system for a room comprising'in combination, means including a hygroscopic dehumidifier, for supplying dehumidiyfied outdoor air into said room, an after cooler for cooling the dehumidifed air delivered by said dehumidifier, a local cooler in said room, supply means for supplying refrigerated water to said coolers, means ,responsive to the dew point temperature of the air delivered by saiddehumidifier l for adjusting the temperature of the water supplied to said coolers by said supply means, means including a dry bulb thermostat exposed t'o the air delivered by said after cooler for adjusting the volume of water from said` supply means to said after cooler, and means including a room thermostat for adjusting the volume of water from said supply means to said local cooler.

11. An air conditioning system for a room comprising in combination, a local cooler in said room, a hygroscopic dehumidifier for supplying dehumidied outdoor-air into said room, an after cooler for cooling the dehumidifled air, means including a duct for delivering the dehumidified cooled air into said room, means responsive to humidity changes in said duct for adjusting the dew pointtemperature of the air delivered by said dehumidifier, supply means for supplying cooling iiuid to said coolers, and means responsive to increases in the dew point temperature of the air in said duct for adjusting said supply means for increasing the temperature of the iluid from said supply means to said coolers. -V

12. An air conditioning system for a room comprising in combination, a local cooler in said room, a hygroscoplc dehumidiiler for supplying dehumidiied outdoor air into said room, an after coolerl for cooling the dehumidiiled air. means including a duct for delivering the dehumidied cooled air into said room, means responsive to humidity changes in said duct for adjusting the dew point temperature ot the air delivered by said dehumidifier, supply means forA supplying cooling water to said coolers, means responsive to the dew point temperature of the air in said duct for adjusting said supply means, volume control means for varying the volume of dehumidiiled air supplied into said room. and

. means including *a room means responsive to humidity changes in said room for adjusting said volume control means.

13. An air conditioning system for a room comprising in combination, a local cooler in said room, a hygroscopic dehumidifier for supplying dehumidiiled outdoor air into said room, an after cooler for cooling the dehumidied air, means including a duct. for delivering the dehumidified cooled air into said room. means responsive to humidity changes in said duct for adjusting the dew point temperature of the air delivered by said dehumidiiiejr. supply means for supplying cooling water to'saidcoolers, means responsive to the dew point temperature of the air in said duct for adjusting the temperature of the water to said coolers from said supply means, means including a duct ltliermostat for varying the volume of water supplied to said after cooler, and thermostat tor varying the volume of water supplied to said room cooler.

HENRY R. SEWELL. 

